1. Field
Example embodiments of the following description relate to a method and apparatus for estimating a three-dimensional (3D) position and orientation based on a sensor fusion process and, more particularly, to a method and apparatus for estimating 3D position and orientation by fusing a result of estimation based on strength information and a result of estimation based on inertial information.
2. Description of the Related Art
Conventionally, techniques that estimate a three-dimensional (3D) position and orientation of a moving object or target have been used in the film, graphic and animation industries, and the like, for sensing motion of an object, a human body, an animal, and the like, in a 3D space using an expensive and large-sized motion capturing device.
As motion sensing techniques for consumer electronics (CE) associated with the game industry have begun to draw attention, many 3D position and orientation estimating methods using an inexpensive and small-sized motion capturing device have been developed.
A 3D position estimating method in a space is classified into three methods, which are a method based on a camera, a method based on an ultrasonic wave, and a method based on an inertial sensor.
According to the method based on the camera, locations of markers or light sources formed in images obtained from a plurality of two-dimensional (2D) cameras are transformed into a 3D position in space. In this case, the performance is dependent on the resolution of the cameras, the size of the markers, and the like, and thus, it may be difficult to perform high precision sensing.
According to the method based on the ultrasonic wave, a distance is calculated by measuring a time of flight (TOF) corresponding to a time taken for an ultrasonic wave to travel from a transmitting unit to a receiving unit and using the fact that ultrasonic waves propagate at the speed of sound, that is, about 340 meters per second (m/s). The 3D position is calculated based on a triangulation process and the like, after obtaining at least three pieces of distance information obtained at the same point of view. The method based on the ultrasonic wave may perform a high precision sensing using a relatively less expensive device than the expensive device, such as the cameras. However, ultrasonic waves are difficult to transmit simultaneously due to inter-sound wave interference, and present a difficulty in estimating a position with respect to a moving object in real time due to a time of attenuation of an ultrasonic wave signal, that is, about 100 milliseconds (ms) taken for a distance of 3 meters (m).
According to the method based on the inertial sensor, the 3D position is calculated by integrating an acceleration component computed, based on an acceleration and a gravity acceleration, obtained through an accelerometer sensor and a gyro-sensor, and an angular velocity. However, the method based on the inertia is able to perform position estimating within a short time period (or window) and is not appropriate for long-time position estimating since errors are accumulated over time.